The present invention relates to new oxide structures which contain octahedral molybdenum and tetrahedral phosphorous combined with transition and/or post-transition metal cations.
Structured, microporous oxides are utilized in a multitude of catalytic and sorption/separation processes in the petroleum and petrochemical industry. The most widely known group of materials that falls within this category are the aluminosilicate zeolites, see Breck, D.W., "Zeolite Molecular Sieves"; Wiley: New York, 1984. A second generation of molecular sieves, high-silica zeolites, were later introduced through the use of organic cations instead of alkali-metal bases traditionally used in zeolite synthesis gels, see Barrer, R.M., Denny, P.J., J. Chem. Soc. 1961, 83, 4675. Recently, a major group of new microporous materials, the aluminophosphates, and related silicoaluminophosphates and metalloaluminophosphates, were also synthesized using organic templating species, see Wilson, S.T., Lok, B.M., Messina, C.A., Cannan, T.R., Flanigen, E.M., J. Am. Chem. Soc. 104, 1147, Lok, B.M., Messina, C.A., Patton, R.L., Gajek, R.T., Cannan, T.R.; Flanigen, E.M., U.S. Pat. No. 4,440,871, 1984, J. Am. Chem. Soc. 1984. 106, 6092, and Messina, C.A., Lok, B.M.; Flanigen, E.M., U.S. Pat. No. 4,544,143, 1985. This latter group of materials demonstrates two very important factors concerning molecular sieves: (1) that three-dimensional microporous materials can crystallize from highly acidic reaction media and (b) components other than silicon and aluminum can be used to generate porous oxide frameworks (in this case, phosphorous, and a variety of different metals).
In addition to all of these tetrahedral framework materials discussed above, there are also other classes of structured microporous solids that contain octahedrally coordinated lattice components as well. These include a previous patent on microporous molybdenum phosphates with organic and alkali metal cations (see U.S. Pat. No. 4,956,483) and a class of microporous molybdenum phosphates based on the Mo.sub.2 P.sub.3 O.sub.12 (OH).sub.2.sup.1- framework (see U.S. Pat. application Ser. No. 648,714). The present invention is also a class of compounds that include octahedral molybdenum and tetrahedral phosphorus. The materials of the present invention differ from the materials described in U.S. Pat. No. 4,956,483 in that transition elements are present in stoichiometric amounts and form an integral part of the covalent three dimensional lattice, i.e., the transition elements bond the molybdenum phosphate portions of the framework together.
Another class of octahedral-tetrahedral framework materials, based on titanium silicates and titanium aluminosilicates, have recently been disclosed in the patent literature, e.g., U.S. Pat. No. 4,853,202 but are obviously compositionally unrelated to the present materials.
The compositions of the present invention are related to zeolites and other microporous materials because they have channels or interlayer spaces capable of reversibly sorbing molecules.